Genetics, Vol. 179, 95-112, May 2008, Copyright © 2008
doi:10.1534/genetics.107.085704

The Chloroplast Protein Translocation Complexes of Chlamydomonas reinhardtii: A Bioinformatic Comparison of Toc and Tic Components in Plants, Green Algae and Red Algae

Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, 3010 Victoria, Australia

1 Corresponding author: Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, 3010 Victoria, Australia.
E-mail: gim{at}unimelb.edu.au

The recently completed genome of Chlamydomonas reinhardtii was surveyed for components of the chloroplast protein translocation complexes. Putative components were identified using reciprocal BlastP searches with the protein sequences of Arabidopsis thaliana as queries. As a comparison, we also surveyed the new genomes of the bryophyte Physcomitrella patens, two prasinophyte green algae (Ostreococcus lucimarinus and Ostreococcus tauri), the red alga Cyanidioschizon merolae, and several cyanobacteria. Overall, we found that the components of the import pathway are remarkably well conserved, particularly among the Viridiplantae lineages. Specifically, C. reinhardtii contained almost all the components found in A. thaliana, with two exceptions. Missing from C. reinhardtii are the C-terminal ferredoxin-NADPH-reductase (FNR) binding domain of Tic62 and a full-length, TPR-bearing Toc64. Further, the N-terminal domain of C. reinhardtii Toc34 is highly acidic, whereas the analogous region in C. reinhardtii Toc159 is not. This reversal of the vascular plant model may explain the similarity of C. reinhardtii chloroplast transit peptides to mitochondrial-targeting peptides. Other findings from our genome survey include the absence of Tic22 in both Ostreococcus genomes; the presence of only one Toc75 homolog in C. merolae; and, finally, a distinctive propensity for gene duplication in P. patens.




This article has been cited by other articles:


Home page
Phil Trans R Soc BHome page
T. Dagan and W. Martin
Getting a better picture of microbial evolution en route to a network of genomes
Phil Trans R Soc B, August 12, 2009; 364(1527): 2187 - 2196.
[Abstract] [Full Text] [PDF]


Home page
Eukaryot CellHome page
M. Kalanon, C. J. Tonkin, and G. I. McFadden
Characterization of Two Putative Protein Translocation Components in the Apicoplast of Plasmodium falciparum
Eukaryot. Cell, August 1, 2009; 8(8): 1146 - 1154.
[Abstract] [Full Text] [PDF]


Home page
Mol PlantHome page
A. Stengel, J. P. Benz, B. B. Buchanan, J. Soll, and B. Bolter
Preprotein Import into Chloroplasts via the Toc and Tic Complexes Is Regulated by Redox Signals in Pisum sativum
Mol Plant, July 6, 2009; (2009) ssp043v1.
[Abstract] [Full Text] [PDF]


Home page
Mol PlantHome page
C. Yoshihara, K. Inoue, D. Schichnes, S. Ruzin, W. Inwood, and S. Kustu
An Rh1-GFP Fusion Protein Is in the Cytoplasmic Membrane of a White Mutant Strain of Chlamydomonas reinhardtii
Mol Plant, November 14, 2008; (2008) ssn074v1.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
O. Vallon and S. Dutcher
Treasure Hunting in the Chlamydomonas Genome
Genetics, May 1, 2008; 179(1): 3 - 6.
[Full Text] [PDF]